The present application claims priority of Japanese Patent Application No. 2000-358566 filed on Nov. 24, 2000, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an electrode-rolled battery, and more particularly relates to an electrode-rolled battery and a method of manufacturing the electrode-rolled battery suitable to supply a large current to a load such as a battery section in an electric car.
2. Description of Related Art
As to an electrode-rolled battery such as a lithium-ion secondary battery, a band-shaped anode and a band-shaped cathode are rolled so that a separator is put between them, and current collecting tabs are connected to active material unformed parts of the anode and cathode. As to a small electrode-rolled battery having a small rated capacity, a strip-type tab is connected to each active material unformed part at each rolling start and each rolling end of the anode and the cathode. As to a large electrode-rolled battery having a large rated capacity, an anode length and a cathode length are longer than those of the small electrode-rolled battery, internal impedance becomes high so as to overheat in vicinities of the tabs since only one tab is connected to each of the cathode and the anode. Therefore, since that is a bad influence on a load characteristic and a cycle lifetime characteristic (that is, a frequency of charge/discharge cycles of the secondary battery repeatedly used until a function of a secondary battery is over), a plurality of tabs are connected to each of the cathode and the anode and a current is collected from a plurality of points.
A large electrode-rolled battery such as this type, conventionally, as shown in FIG. 12, is provided with a rolled body 10 and a plurality of tabs (a tab 20, a tab 21, a tab 22, and a tab 23). The rolled body 10 is stored in a cylindrical case (not shown). The rolled body 10 is formed by rolling a band-shaped anode 11 and a band-shaped cathode 12 so as to put a separator 13 between them. The tab 20, the tab 21, the tab 22, and the tab 23 are respectively connected to four anode active material unformed parts 11 a (after mentioned) in the anode 11. Similarly, other tabs (not shown) are connected to the cathode 12.
FIG. 13A and FIG. 13B show the anode 11 in FIG. 12, and FIG. 13A is a view showing a peripheral surface viewed from an arrow A in FIG. 12 and FIG. 13B is a plan unrolled view showing the anode 11.
As shown in FIG. 13A, in the rolled body 10, a central axis is set as xe2x80x9cOxe2x80x9d, and a radius is set as xe2x80x9cRxe2x80x9d when the anode active material unformed parts of the cathode 11 exist in a peripheral surface of the rolled body 10. As shown in FIG. 13B, in the anode 11, the anode active material forming parts 11a are formed in a longitudinal direction of a band-shaped current collector 11p intermittently. The tab 20, the tab 21, the tab 22, and the tab 23 are respectively connected to anode active material unformed parts 11b between the anode active material forming parts 11a. Each the anode active material unformed parts 11b is formed at regular intervals and has a regular length. A length L1 is set as follows:
L1 less than 2xcfx80R.
Further, the tab 20, the tab 21, the tab 22, and the tab 23 are connected to a same position of each of the anode active material unformed parts 11b. The cathode 12 is formed similarly to the anode 11.
FIG. 14 is a view showing an essential part of the rolled body 10 indicated by the arrow A in FIG. 12.
In the rolled body 10, as shown in FIG. 14, the anode 11 and the cathode 12 are rolled in a rolling direction S so that a separator (not shown) is put between the anode 11 and the cathode 12. To prevent Li+ ions in the anode active material from depositing as metallic lithium between the anode 11 and the cathode 12, a deviation d1 is set between a start point of the anode active material unformed part 11b and a start point of a cathode active material unformed part 12b which is opposite to the anode active material unformed part 11b and a deviation d2 is set between an end point of the anode active material unformed part 11b and an end point of the cathode active material unformed part 12b which is opposite to the anode active material unformed part 11b. 
The electrode-rolled battery is represented by, for example,
(xe2x88x92) Cn|LiPF6xe2x88x92PC/DEC|Li1+yMn2O4(+),
where LiPF6 is lithium, PC is propylene carbonate (electrolyte) and DEC is diethyl carbonate (electrolyte).
A battery reaction is represented by:
Charge
LiMO2+CnLi1xe2x88x92xMO2+CnLix,
Discharge
xe2x80x83Charge
Li1+yMn2O4+CnLi1+yxe2x88x92xMn2O4+CnLiX,
Discharge
where LiMO2 is lithium metallic oxide (anode active material), xe2x80x9cMxe2x80x9d is Co, Ni or Fe and xe2x80x9cCnxe2x80x9d is carbon material (cathode active material).
FIG. 15A to FIG. 22 are process diagrams for explaining a method of manufacturing the electrode-rolled battery shown in FIG. 12.
Manufacturing process (1) to manufacturing process (8) of the electrode-rolled battery shown in FIG. 12 will be explained with reference to FIG. 15A to FIG. 22.
(1) Manufacturing process is shown in FIG. 15A and FIG. 15B.
As shown in FIG. 15A, anode active material forming parts 11a, are intermittently provided on one side of the band-shaped current collector 11p in the longitudinal direction. Parts except the anode active material forming parts 11a are anode active material unformed parts 11b. A length of each anode active material unformed part 11b is set to length L1. Similarly, the anode active material forming parts 11a are intermittently provided on another side of the band-shaped current collector 11p in the longitudinal direction. As shown in FIG. 15B which is a sectional view of FIG. 15A taken along a line Axe2x80x94A of FIG. 15A, an anode 11 is manufactured in a manner that the anode active material forming parts 11a are formed on both sides of the band-shaped current collector 11p. 
(2) Manufacturing process is shown in FIG. 16A and FIG. 16B.
As shown in FIG. 16A, cathode material forming parts 12a are intermittently provided on one side of the band-shaped current collector 12p in the longitudinal direction. In this case, parts except the cathode active material forming parts 12a are cathode active material unformed parts 12b. Similarly, the cathode active material forming parts 12a are intermittently provided on another side of the band-shaped current collector 12p in the longitudinal direction. As shown in FIG. 16B which is a sectional view of FIG. 16A taken along a line Bxe2x80x94B, a cathode 12 is manufactured in a manner that the cathode active material forming parts 12a are formed on both sides of the band-shaped current collector 12p. 
(3) Manufacturing process is shown in FIG. 17.
A tab 20, a tab 21, a tab 22, and a tab 23 are respectively connected to the anode active material unformed parts 11b. 
(4) Manufacturing process is shown in FIG. 18.
A tab 30, a tab 31, a tab 32, and a tab 33 are respectively connected to the cathode active material unformed parts 12b. 
(5) Manufacturing process is shown in FIG. 19.
A separator 13 is put between the anode 11 and the cathode 12 and they are rolled by a rolling apparatus so as to manufacture the rolled body 10. Incidentally, the tab 30, the tab 31, the tab 32, and the tab 33 are not shown since they are pulled out from another side not a side from which the tab 20, the tab 21, the tab 22, and the tab 23 are pulled out.
(6) Manufacturing process is shown in FIG. 20.
The tab 20, the tab 21, the tab 22, and the tab 23 are gathered by a manual operation F of an operator. Similarly, the tab 30, the tab 31, the tab 32, and the tab 33 (not shown) are gathered.
(7) Manufacturing process is shown in FIG. 21.
A collecting header 24 is connected to the tab 20, the tab 21, the tab 22, and the tab 23 by manual operation of the operator, so as to perform ultrasonic welding. Similarly, a header (not shown) is connected to the tab 30, the tab 31, the tab 32, and the tab 33 (not shown). Then, the rolled body 10 is stored in a cylindrical case (not shown).
(8) Manufacturing process is shown in FIG. 22.
Electrolyte is injected by an electrolyte injecting nozzle N in a direction from which the tab 20, the tab 21, the tab 22, and the tab 23 are pulled out, and then the electrode-rolled battery is completed. Incidentally, the header 24 is not shown in FIG. 22.
FIG. 23A to FIG. 26 are process diagrams for explaining a method of manufacturing another conventional electrode-rolled battery.
Manufacturing process (1) to manufacturing process (4) of another electrode-rolled battery will be explained with reference to FIG. 23A to FIG. 26:
(1) Process is shown in FIG. 23A and FIG. 23B.
As shown in FIG. 23A, an anode active material forming part 14a is continuously provided on one side of a band-shaped current collector 14p except one end in a width direction. A part except the anode active material forming parts 14a is an anode active material unformed part 14b. Similarly, an anode active material forming part 14a is continuously provided on another side of the band-shaped current collector 14p except one end in the width direction. As shown in FIG. 23B which is a sectional view of FIG. 23A taken along a line Cxe2x80x94C, an anode 14 is manufactured in a manner that the anode active material forming part 14a and the anode active material forming part 14a are formed on both sides of the electrode 14p. 
(2) Process is shown in FIG. 24A and FIG. 24B.
As shown in FIG. 24A, a cathode active material forming part 15a is continuously provided on one side of a band-shaped electrode 15p except one end in the width direction. In this case, a part in addition to the cathode active material forming part 15a is a cathode active material unformed part 15b. Similarly, the cathode active material forming part 15a is continuously provided on another side of the band-shaped current collector 15p except one end in the width direction. As shown in FIG. 24B which is a sectional view of FIG. 24A taken along a line Dxe2x80x94D, a cathode 15 is manufactured in a manner that the cathode active material forming part 15a and the cathode active material forming part 15a are formed on both sides of the band-shaped current collector 15p. 
(3) Process is shown in FIG. 25.
The tab 20, the tab 21, the tab 22, and the tab 23 are connected to the anode active material unformed-part 14b at regular intervals.
(4) Process is shown in FIG. 26.
The tab 30, the tab 31, the tab 32, and the tab 33 are connected to the cathode active material unformed part 15b at regular intervals. Then, same processes as shown in FIG. 19 to FIG. 22 are performed.
However, there are the following problems in the above-mentioned electrode-rolled battery.
That is, since the length L1 of the anode active material unformed part 11b is shorter than 2xcfx80R, it is impossible to arrange the tab 20, the tab 21, the tab 22, and the tab 23 regularly, for example, in a line. Therefore, there is a problem in that processes of gathering the tab 20, the tab 21, the tab 22, and the tab 23 and of connecting them to the header 24 (that is, processes shown in FIG. 20 and FIG. 21) are not only complicated but also it is difficult to perform these processes using an apparatus. Particularly, in a case in that the header 24 is ring-shaped or disc-shaped, when the tab 20, the tab 21, the tab 22, and the tab 23 are irregularly pulled from a plurality of positions in the end of the rolled body 10, there is a problem in that the process of connecting the header 24 to the tab 20, the tab 21, the tab 22, and the tab 23 and of performing ultrasonic welding (namely, process shown in FIG. 21) becomes difficult. Further, in the process of injecting the electrolyte (namely, the process shown in FIG. 22), the tab 20, the tab 21, the tab 22, and the tab 23 become obstacles, it is difficult to insert the electrolyte injecting nozzle N and there is a problem in that the injecting operation is complicated.
Further, since it is impossible to set positions of the tab 20, the tab 21, the tab 22, and the tab 23 freely, it is impossible to disperse the positions of the tab 20, the tab 21, the tab 22, and the tab 23 so that an internal impedance of the rolled body 10 is small, there is a case in that an internal impedance of the rolled body 10 is large. As a result, when a large current is continuously supplied from the electrode-rolled battery to a load, the rolled-body 10 heats and the electrolyte degrades, and therefore, there is a problem in that a cycle lifetime characteristic of the electrode-rolled battery degrades. Also, since it is impossible to set positions of the tab 20, the tab 21, the tab 22, and the tab 23 freely, in a case in that positions of the anode active material forming parts 11a are set so that pulling positions of the tab 20, the tab 21, the tab 22, and the tab 23 are arranged in a line in a diameter direction of the rolled body 10, the rolled body 10 is not provided with an originally-designed structure caused by parameters such as a thickness accuracy of the anode 11, a thickness accuracy of the cathode 12, and an accuracy of the rolling force of a rolling apparatus, and therefore, there is a problem in that a desired characteristic can be obtained and there is no stability in the characteristic.
Further, the anode 14 shown in FIG. 25, areas for contacting the tab 20, the tab 21, the tab 22, and the tab 23 with the anode active material unformed part 14b are smaller than the anode 11 shown in FIG. 17. Therefore, there is a problem in that the internal impedance of the rolled body 10 is large. Also, there are many cases in that the anode 14 is in a wavy form caused by differences such expansions between the anode active material forming part 14a and the anode active material unformed part 14b during the manufacturing process, and therefore, there is a case in that the anode 14 is not suitable for use. Similarly, there is a case in that the cathode 15 shown in FIG. 26 is not suitable for use.
In view of the above, it is an object of the present invention to provide an electrode-rolled battery suitable to supply a large current and manufactured by a simple process and to provide a method of manufacturing the electrode-rolled battery.
According to a first aspect of the present invention, there is provided an electrode-rolled battery in which an anode and a cathode are rolled in a manner that a separator is put between the anode and the cathode and in which a plurality of collecting tabs is respectively connected with a plurality of cathode active material unformed parts and a plurality of anode active material unformed parts; and
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, a following expression is set:
Lxe2x89xa72xcfx80R.
According to a second aspect of the present invention, there is provided an electrode-rolled battery in which an anode and a cathode are rolled in a manner that a separator is put between the anode and the cathode and in which a plurality of collecting tabs is respectively connected with a plurality of cathode active material unformed parts and a plurality of anode active material unformed parts; and
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, when a deviation between a start point of the outermost anode active material unformed part and a start point of a outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9cxcex1xe2x80x9d, and when a deviation between an end point of the outermost anode active material unformed part and an end point of the outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9cxcex2xe2x80x9d, a following expression is set:
L=2xcfx80R+xcex1+xcex2.
According to a third aspect of the present invention, there is provided an electrode-rolled battery comprising:
an anode having a first band-shaped current collector and intermittently having anode active material forming parts on both sides of the first band-shaped current collector in a longitudinal direction;
a cathode having a second band-shaped current collector and intermittently having cathode active material forming parts on both sides of the first band-shaped current collector in a longitudinal direction;
a plurality of first collecting tabs formed in the anode active material unformed parts of the first band-shaped current collector;
a plurality of second collecting tabs formed in the cathode active material unformed parts of the second band-shaped current collector; and
a separator put between the cathode and the anode;
the electrode-rolled battery in which the anode, the cathode and the separator are rolled; and
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, a following expression is set:
Lxe2x89xa72xcfx80R.
According to a fourth aspect of the present invention, there is provided an electrode-rolled battery comprising:
an anode having a first band-shaped current collector and intermittently having anode active material forming parts on both sides of the first band-shaped current collector in a longitudinal direction;
a cathode having a second band-shaped current collector and intermittently having cathode active material forming parts on both sides of the second band-shaped current collector in a longitudinal direction;
a plurality of first collecting tabs formed in the anode active material unformed parts of the anode;
a plurality of second collecting tabs formed in the cathode active material unformed parts of the cathode; and
a separator put between the cathode and the anode;
the electrode-rolled battery in which the cathode, the anode and the separator are rolled; and
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, when a deviation between a start point of the outermost anode active material unformed part and a start point of a outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9cxcex1xe2x80x9d, and when a deviation between an end point of the outermost anode active material unformed part and an end point of the outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9cxcex2xe2x80x9d, a following expression is set:
L=2xcfx80R+xcex1+xcex2.
In the foregoing, a preferable mode is one wherein each of the collecting tabs is arranged regularly on an end face of the rolled body.
According to a fifth aspect of the present invention, there is provided a method of manufacturing an electrode-rolled battery in which an anode and a cathode are rolled in a manner that a separator is put between the anode and the cathode and in which a plurality of collecting tabs is respectively connected with a plurality of cathode active material unformed parts and a plurality of anode active material unformed parts; and
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, a following expression is set:
Lxe2x89xa72xcfx80R.
According to a sixth aspect of the present invention, there is provided a method of manufacturing an electrode-rolled battery in which an anode and a cathode are rolled in a manner that a separator is put between the anode and the cathode and in which a plurality of collecting tabs is respectively connected with a plurality of anode active material unformed parts and a plurality of cathode active material unformed parts; and
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, when a deviation between a start point of the outermost anode active material unformed part and a start point of a outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9caxe2x80x9d, and when a deviation between an end point of the outermost anode active material unformed part and an end point of the outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9cPxe2x80x9d, a following expression is set:
L=2xcfx80R+xcex1+xcex2.
According to a seventh aspect of the present invention, there is provided a method of manufacturing an electrode-rolled battery comprising:
an anode forming process of forming an anode by intermittently forming anode active material forming parts on both sides of a first band-shaped current collector in a longitudinal direction;
a cathode forming process of forming a cathode by intermittently forming cathode active material forming parts on both sides of a second band-shaped current collector in a longitudinal direction;
a connecting process of connecting a plurality of first collecting tabs to anode active material unformed parts of the first band-shaped current collector and of connecting a plurality of second collecting tabs to cathode active material unformed parts of the second band-shaped current collector;
a rolling process of rolling the cathode and the anode, and a separator which is put between the cathode and the anode;
a first tab gathering process of gathering each of the first collecting tabs;
a header connecting process of connecting a collecting header to the first collecting tabs which are gathered;
a second tab gathering process of gathering each of the second collecting tabs;
an electrolyte injecting process of injecting electrolyte into the rolled body using an electrolyte injecting apparatus:
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, a following expression is set:
Lxe2x89xa72xcfx80R.
According to an eighth aspect of the present invention, there is provided a method of manufacturing an electrode-rolled battery comprising:
an anode forming process of forming an anode by intermittently forming anode active material forming parts on both sides of a first band-shaped current collector in a longitudinal direction;
a cathode forming process of forming a cathode by intermittently forming cathode active material forming parts on both sides of a second band-shaped current collector in a longitudinal direction;
a connecting process of connecting a plurality of first collecting tabs to anode active material unformed parts of the first band-shaped current collector and of connecting a plurality of second collecting tabs to cathode active material unformed parts of the second band-shaped current collector;
a rolling process of rolling the cathode and the anode, and a separator which is put between the cathode and the anode;
a first tab gathering process of gathering each of the first collecting tabs;
a header connecting process of connecting a collecting header to the first collecting tabs which are gathered;
a second tab gathering process of gathering each of the second collecting tabs;
an electrolyte injecting process of injecting electrolyte into the rolled body using an electrolyte injecting apparatus; and
wherein when a length of an outermost anode active material unformed part is set as xe2x80x9cLxe2x80x9d; and when a distance from the outermost anode active material unformed part to a center of a rolled body made up of the anode, the cathode and the separator, is set as xe2x80x9cRxe2x80x9d, when a deviation between a start point of the outermost anode active material unformed part and a start point of a outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9cxcex1xe2x80x9d, and when a deviation between an end point of the outermost anode active material unformed part and an end point of the outermost cathode active material forming part which is opposite to the outermost anode active material unformed part is set as xe2x80x9cxcex2xe2x80x9d, a following expression is set:
xe2x80x83L=2xcfx80R+xcex1+xcex2.
In the foregoing, a preferable mode is one wherein each of the collecting tabs is arranged regularly on an end face of the rolled body.
According to the present invention, since a length L of the outermost anode active material unformed part is set as follows:
Lxe2x89xa72xcfx80R(for example, L=2xcfx80R+xcex1+xcex2),
the first collecting tabs can be arranged regularly, for example, the first collecting tabs are pulled in a line in a diameter direction of the rolled body or are equally dispersed on the circumstance of the rolled body. Therefore, the process of gathering the first collecting tabs (first tab gathering process) and the process of connecting gathered first collecting tabs to the header (header connecting process) are made simple when compared with a conventional technique. Further, since the first collecting tabs can be arranged regularly, in the process of injecting electrolyte to the rolled body in the electrolyte injecting process, an electrolyte injecting nozzle apparatus is easily inserted, and therefore, the operation is made easier than the conventional technique.
Further, since it is possible to set the first collecting tabs at any position, it is possible to set an internal impedance of the rolled body small. Therefore, though a large current is continuously supplied from the electrode-rolled battery to a load, there is no case in that the rolled body heats and the electrolyte degrades, and therefore, a cycle lifetime characteristic of the electrode-rolled battery improves in comparison with a conventional electrode-rolled battery. Also, it is possible to set the first collecting tabs freely, and therefore, though in the anode, the anode active material forming parts are positioned so that the first collecting tabs are pulled in a line in the diameter direction of the rolled body, it is possible to manufacture the electrode-rolled battery based on an original design without influences of parameters such as thickness accuracy of the anode, thickness accuracy of the cathode, and rolling force of the rolling apparatus, to obtain a desired characteristic and to manufacture electrode-rolled batteries without characteristic deviations.